Apparatus for testing oil wells using annulus pressure

ABSTRACT

An annulus pressure operated oil well testing and sampling apparatus utilizes hydrostatic pressure to supplement spring means which biases against valve means to hold the valve means closed until application of sufficient hydraulic pressure to the annular fluid opens the tool to the formation and allows testing operations to be performed. A subsequent intentional or inadvertent release or sudden extreme increase of applied pressure on the annular fluid actuates means to close the valve means against further formation fluid flow.

Jan. 7, 1975 United States Patent 1191 Wray et al.

5 l XXXX HAI AI-P\1HNI-H UMWU 7// /7 .66 6. 66 6 MMLM mm "t t. u "etc nmi aw Vin H auflfl .m OUu KMWYNN 222344 777777 999999 HHHHHH 235677555530 O9 075 3 1 364 34 446422 1 .7 333333 l APPARATUS FOR TESTING OILWELLS USING ANNULUS PRESSURE [75] Inventors: Gary Q. Wray; John C.Holden,

both of Duncan, Okla.

[73] Assignee:

Halliburton Company, Duncan, Okla" I Primary Examiner-David H. BrownAttorney, Agent, or Firmlohn H. Tregoning; Floyd A. Gonzales [22] Filed:May 17, 1974 App]. N6; 471,119

[57] ABSTRACT An annulus pressure operated oil well testing and sam-Related US. Application Data Continuation of Ser. No. 335,980, Feb. 26,l973, abandoned.

pling apparatus utilizes hydrostatic pressure to supple- [56] ReferencesCited UNITED STATES PATENTS 3,456,726 7/1969 Barrington et 166/162 22Claims 15 Drawing Figures PATENTED JAN 7 7 SHEET 1 OF 8 FIG.2

FIG.1

PATEHTEBJAN 1191s SHEET 3 BF 8 FIG. 3d

PATENTED 71975 SHEET 7 UF 8 F I G; 40

SHEET 8 BF 8 APPARATUS FOR TESTING OIL WELLS USING ANNULUS PRESSURE Thisis a continuation, of application Ser. No. 335,980, filed Feb. 26, 1973,now abandoned.

BACKGROUND OF THE INVENTION This invention is directed towards testingof oil wells and is specifically advantageous in offshore and underwaterwells.

After an oil well has been encased and cemented it usually becomesdesirable to test the formations penetrated by the wellbore for possibleproduction rates and general potential of the well. In doing so, a teststring containing several different types of tools is utilized todetermine the productivity of the well. These tools may include apressure recorder, a sample chamber, a closed-in pressure tester, anhydraulic jar, one or more packers, a circulating valve, and possiblyseveral other tools.

The testing procedure requires the opening of a section of the wellboreto atmospheric or reduced pressure. This is accomplished by lowering thetest string into the hole on drill pipe with the tester valves andsample chamber closed to prevent entry of well fluid into the drillpipe. With the string in place in the formation, packers are expanded toseal against the wellbore or casing to isolate the formation to betested. Above the formation the hydrostatic pressure of the well fluidis supported by the upper packer. The well fluid in the isolatedformation area is allowed to flow into the drill string by opening thetester valve. Fluid is allowed to continue flowing from the formation tomeasure the ability of the formation to produce. The formation may thenbe closed in to measure the rate of pressure buildup. After the flowmeasurements and pressure buildup curves have been obtained, samples canbe trapped and the test string removed from the well.

Previously the method used to open and close the necessary valves andchambers in the tool string involved physical manipulations of thestring either in vertical reciprocation or rotational motion or acombination of both. Another method involved use of heavy bars or ballsdropped down the string to actuate certain tools in the string.

All of these methods suffer thee serious disadvantage of requiringmovement of or within the drill pipe. This is especially disadvantageousin offshore drilling because of the danger of drill pipe separation orblowout during the period the blowout preventer rams are removed fromthe drillpipe during the manipulation of the string or dropping ofobjects down the pipe.

One means of operating tools in the testing string without manipulationof the pipe which has proven very successful involves the use of annuluspressure operated testing tools. Examples of these tools include theannulus pressure responsive (APR) safety sampler disclosed in U.S. Pat.No. 3,664,415, the APR disc valve disclosed in U.S. Pat. applicationSer. No. 224,755 filed Feb. 9. 1972, now U.S. Pat. No. 3,779,263, andthe APR circulating valve disclosed in U.S. Pat. application Ser. No.288,187 filed Sept. II, 1972, all assigned to the assignee of thisapplication, Halliburton Company.

While this family of annulus pressure operated testing and samplingtools offers substantial advancements over the mechanically operatedtools previously discussed, the present invention discloses a secondgeneration APR tool having even further advantages over those of thefirst generation.

Use of the above-mentioned first generation APR tool string requires afairly accurate knowledge, either empirical or calculated, of thebottomhole conditions in the well immediately prior to running therequired tests. This is because the inert gas chamber in these toolswhich serves as a spring biasing means must be charged at apredetermined pressure and volume to offset the hydrostatic pressure andtemperature at hottomhole and still retain sufficient springing actionto allow the tool to operate in response to surface applications ofhydraulic pressure on the annulus fluid and to close the tool uponrelease ofthe applied annulus pressure. In the case of fairly deepwells, this requires the charging of the inert gas spring chamber toextremely high pressures, on the order of 10,000 psi and above, on theground before going in the hole, which pressures require extra thickchamber walls and other precautionary measures for safetys sake.

The present invention overcomes these disadvantages by providing a toolwhich can be charged with inert gas at a relatively low pressure levelon the ground and then utilizes hydrostatic pressure to supplement thispressure as the tool travels down the borehole, so that when the APRtool reaches the bottom of the hole there will be sufficient pressure inthe tool gas chamber to provide a springing action above the pressureestablished by hydrostatic forces and gas expansion due to the hightemperature rise. As the tool is removed from the well, hydrostaticsupplementary pressure is gradually removed from the tool.

The tool of this invention, in addition to serving as a testing tool andsampler, also operates as a safety valve in case the drill string partsor leaks or other emergency arises which takes the weight off of thestring. The tool also provides a lock-closed feature which automaticallycloses the tool in case of a large pressure rise in the casing.Furthermore, it features a full-open drill-pipe bore from ground surfaceto the sampler depth.

This invention achieves its objectives by the use of multiple floatingpiston means, and multiple gas chambers in conjunction with shuttlevalves and pressure balanced valves.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 provides a schematic, vertical,elevational view of an offshore test site, illustrating a testing stringdisposed in a submerged well and intersecting a submerged formation;

FIG. 2 illustrates an enlarged, vertically sectioned, fragmentaryelevational view of a well head portion of the assembly of FIG. I,located on a floating vessel or work station, and a submerged well headportion having an annulus pressure responsive system;

FIGS. 3a through 3h when joined along common lines aa through g-g,provide an enlarged, vertically sectioned, right-side only view of thepower section of the APR tools;

FIGS. 4a through 4d when joined along common lines a-a through c--c,provide an enlarged, vertically sectioned, right-side only view of theseparable sampler of the APR tool; and

FIG. 5 is an elevational side view of the pull mandrel yoke.

DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 schematicallyillustrates a representative offshore test operation.

As shown in FIG. I, a floating drilling vessel or work station 1 isanchored or otherwise secured in position over a submerged well site 2.Submerged well site 2 comprises a bore hole 3, the interior of which maybe lined by a casing string 4 in a conventional fashion.

Wellbore 3, and usually casing 4, intersect a formation 5 whoseproductivity is to be tested.

Where casing 4 intersects formation 5, at area 3a, perforations willusually be provided to ensure fluid communication between the formation5 and the interior 6 of the wellbore 3.

At the submerged mud-line a submerged wellhead installation 7 may beprovided. Installation 7 may be provided with a variety of blow-outpreventer mechanisms of both the partial closing and blind type, thestructure and operation of which are generally shown in FIG. 2 of UnitedStates Manes et al., U.S. Pat. No. 3,646,995 filed Dec. 8, 1969, andassigned to the assignee of the present application.

As will be understood, submerged wellhead 7 may also comprise any ofseveral conventional off the shelf submerged wellhead units nowavailable.

A marine conductor 8 extends upwardly from wellhead 7 to floating workstation I and may be laterally supported on deck means 9 of work station1, generally as schematically shown in FIG. 2. The upper end ofconductor 8 may pass slidably through a gimbal connection on deck 9.Such an arrangement, known in the art, provides lateral support forconductor 8 while permitting wave action induced, vertical movement ofstation 1 relative to the conductor. Conductor slip joints might also beused to accommodate wave action.

A testing string 10 is manipulated at work station 1 by conventionalhoisting means 11, conventionally operated from a derrick-like structure12A, as shown in FIG. 1. The usual control head, manifold andswivelarrangements may be provided in the upper end of string 10 topermit conventional circulation of fluid through the testing string androtary testing string manipulations.

This hoisting means, in conjunction with conventional rotary table slipmeans would be employed to threadably interconnect sections of the teststring 10 and lower the test string 10 through the marine conductor 8and casing 4 to the general disposition shown in FIG. I.

As shown in FIG. 2, test string 10 will be disposed in slidable butsealing engagement with a wellhead seal 12. Wellhead seal 12 maycomprise a conventional flow head or circulating head mounted on awellhead closure 13 and defining a transverse annular barrier extendingacross the upper end of marine conductor 8. As will thus be appreciated,elements 13 and 12 cooperate to provide a seal between the upper end ofmarine conductor 8 and the exterior of the conduit or test string 10.

A pressuring fluid supply conduit 14, possibly a conventional, safetyvalve controlled, mud or kill line may extend from site 1, downwardlyalong the exterior of conductor 8, and intersect the wellhead 7 belowits blowout preventers, generally as shown in FIG. 2. Such a kill linewould usually be attached to the exterior of conductor 8 and wouldcommunicate with the upper interior of casing 4. Conduit 14 extends to aconventional mud pump" 15 on floating site 1. Pump 15 is used to impartpressure to fluid, possibly of a conventional drilling mud nature,contained within and substantially filling the annular void or space 16surrounding the conduit string 10, and disposed between the string 10and casing 4 beneath the wellhead 7.

String 10 may include the following components, disposed inconsecutively downwardly spaced relation:

As shown in FIG. I, with the testing string 10 installed in position,the packer 27 will have been manipulated to expanded condition so as toprovide a seal between the conduit string 10 and the bore hole wall 4.Packer 27 may desirably be of the type shown in Anderson et al., U.S.Pat. Nos. 3,584,684 and 3,702,634, filed June 2, 1969, assigned to theassignee of the present application.

This packer mechanism is operated in response to rotary and linearmanipulations of the conduit string as described in the aforesaidAnderson et al. patents, with sufficient operating weight or movementbeing transmitted through the string by virtue of the presence of suchweight providing elements in the string as the conduit means 21. Suchweight is desirable in a testing string of this nature because of theexpansible and contractible character of the torque transmitting, buttelescoping, slip joint coupling 20. With the weighting elementsincluded in string 10 below coupling 20, downward or upward movment ofthe conduit string, during its installation, will be effectivelytransmitted through the string to the operating components of the packermechanism 27.

After setting of the packer has been initiated, the slip joint 20 willbe disposed in a partially contracted condition, the weight of upperelements 17 and 18 of string 10 will be supported by closed blowoutpreventer rams in wellhead 7, and the drilling vessel 1 will be free tomove up and down in relations to the upper end of test string 10. Themanner of effecting packer setting as above indicated and the manner inwhich wellhead rams provide upper test string support by engaging testtree associated abutment means is fully described in the aforesaid Maneset al. patents.

During the packer setting, the slip joint 20 effectively isolates waveaction induced force from being transmit ted through the upper portionof string 10 to the packer 27, as described in the aforesaid Manes etal. patents. The slip joint 20 also permits some tolerance in the extentof downward movement of the upper conduit string portion, afterinitiation of packer setter, required to seat test tree abutment meanson the closed rams in wellhead 7.

Since the slip joint 20 permits the upper end of the string to be seatedon, i.e., supported by, wellhead 7, it permits the string 10 to bedisconnected from fully supported relation with the hoisting mechanismof the vessel 1 and thus isolated from wave actions acting on thisvessel. Even if string 10 should remain supported by this hoistingmechanism, the telescoping action of the slip joint would prevent thetransmission of wave actions to the portion of string 10 below the slipjoint.

With the testing string 10 manipulated so as to seat or expand thepacker 27, the expanded packer will provide a seal between the conduitstring 10 and the casing or bore hole wall 4, defining the closed lowerend of annular void or space 16. With this arrangement, annular space 16will be effectively isolated from the interior of the conduit string 10and from the formation 5. In the embodiment described, the closed ramsin wellhead 7, upon which test tree abutment means is seated, willprovide an annular closure in wellbore 3, defining a closed upper end ofannulus 16. Thus, with annulus 16 filled with fluid, such as mud, line14 will serve to convey pressurized fluid to annulus 16 and increase itspressure, depending on the height of line 14 and the pressure of fluidit conveys.

Even if the support rams in wellhead 7 should not define an annulus sealat wellhead 7, the annular cavity above wellhead 7 between string 10 andeasing 4 will be filled with fluid, possibly mud. This body of fluidwill define an upper extension or portion of annulus 16, sealed at itsupper end by means 12 and 13.

Indeed, in certain circumstances, it may be desirable for the entireweight of the portion of conduit string 10 above slip joint to besupported by hoist mechanism 11, with slip joint 20 being partiallycontracted to absorb wave action and the rams of wellhead 7 open. Thisarrangement would provide an annulus 16 extending from packer 27 toconductor closure 13. Pressurizing of such an elongated annulus 16 couldbe effected by a pressurizing line 14 communicating with the interior ofthe conductor 8 at the elevation of the vessel 1.

The test tree mechanism 18 incorporated in the conduit string maycomprise the safety mechanism described in the aforesaid Manes et al.patent, assigned reference numeral 801 in the Manes et al. patent, andcommercially available from Otis Engineering Corporation, Post OfficeBox 34380, Dallas, Texas 75234. This mechanism 18 comprises anhydraulically operable valve assembly for selectively closing off oropening the interior passage of the string 10 in the vicinity of thesubmerged wellhead installation 7. The mechanism 18 is designated byOtis Engineering Corporation as a retrievable subsea test tree, thestructure and function of the apparatus being described in greaterdetail in the aforesaid Manes et al. patent.

The slip joint mechanism 20 may desirably comprise a pressure and volumebalanced slip joint of the type described in Hyde US. Pat. No.3,354,950. The Hyde slip joint comprises an extensible and contractible,telescoping coupling in the conduit string 10, which coupling ispressure and volume balanced, telescoping in nature, and operable toeffectively minimize or eliminate the transmission of wave actioninduced force acting on the upper portion of the conduit string 10 andthe floating vessel 1 from being transmitted through the conduit string10 to the packer 27 and the valving and sample entrapping mechanism 25.

With this basic disposition of components, a valving mechanism includedin the device 25 may be operated so as to close the longitudinallyextending interior passage of the conduit string 10, open this passage,or close the passage so as to entrap a sample of formation fluid withthe body or conduit means portion of the mechanism 25.

As the valving elements ofthe mechanism 25 are manipulated, the pressurerecorders 24 and 26, disposed respectively above and below the mechanism25, will continuously record the pressure of formation fluid at thesesites in the conduit string, in a well recognized fashion.

During the testing operation, or during the removal of the testingstring, or during its installation, it may be desirable to effect acirculation of fluid between the interior of the conduit string and theannular space 16. Such circulation of fluid is permitted by thecirculating valve 22, which normally is disposed in a closed condition.Valve 22 may comprise a ratchet-type annulus pressure operated sleevevalve such as that disclosed in US. Pat. application, Ser. No. 288,187in the names of John C. Holden and Gary Q. Wray, also assigned to theassignee of this application.

As is often done, from a safety standpoint, the testing string 10 mayinclude a jar mechanism, anticipating the possibility that release ofthe packer 27 may be impeded for a variety of operational reasons. Aneffective jarring mechanism which may be utilized for this purpose, andwhich may be incorporated in the test string above the packer 27, andbeneath the recorder 26, comprises an hydraulic jarring mechanism of thetype generally featured in Barrington US. Pat. No. 3,429,389, or of thetype featured in Barrington US. Pat. No. 3,399,740.

As a further safety feature, the test string 10 may include asafetyjoint" incorporated between the jarring mechanism and the packer27. A safety joint uniquely suitable for such incorporation is featuredin Barrington US. Pat. No. 3,368,829. The safety joint would permit thetesting string to be disconnected from a stuck packer assembly andremoved to the work site.

While the arrangements heretofore described afford the unique advantageof an open or unobstructed inte' rior of string 10 extending downwardlyfrom vessel 1 to mechanism 25, it might be desirable, at times, toutilize additional passage blocking, safety equipment. Thus, asdescribed in the aforesaid Manes et al. patent, the lower end of theslip joint 20 might be connected with a test string, passagecontrolling, reciprocation responsive safety valve, designated item 12in the Manes et al. disclosure.

Under certain conditions, the packer 27 may not be attached to the teststring 10. For example, a drillable test packer could be previously setby a wire line" and the test string later lowered and coupled with thepacker via a probe or stinger carried by the test string. Such anarrangement is generally described in Evans et al. US. Pat. No.3,423,052.

With the overall installation and test string having been generallydescribed and various alternatives discussed, it now becomes appropriateto consider the general operating characteristics of this invention asreflectingin the structure and operating characteristics of the valvingand sample entrapping mechanism 25.

DETAILED POWER SECTION CONSTRUCTION The sampling mechanism 25essentially comprises two sections, the power section 30 and theseparable sampler section 40.

The power section 30 which occupies the upper part of the mechanism isshown in detail in FIGS. 30 through 3h. This section, beginning at thetop, has an upper adapter 301 having internal threads 302 at the top forconnecting in the drill string and external threads 303 on a reduceddiameter skirt 304 at the bottom for attachment to the power section 30.Attached to threads 303 is the hydrostatic pressure balanced port valveassembly 305 utilized to prevent the bouyancy of the tool from closingthe hydrostatic pressure ports 306 when entering the well fluid.Assembly 305 comprises a cylindrical upper housing 307 atached to acylindrical lower housing 308, a cylindrical piston mandrel 309 slidablylocated within outer housings 307 and 308, and coil compression spring310. Ports 306 pass through the wall of housing 308.

Inner piston mandrel 309 comprises a cylindrical sleeve having anintegral annular external piston shoulder 311 and external splines 312located thereon. Piston shoulder 311 has annular seal grooves 313 on itsouter surface for receiving O-ring seals 314 therein. Upper housing 307has an enlarged inner chamber 315 for sealingly receiving pistonshoulder 311 in slidable relationship therein. Housing 307 furthermorehas internal splines 316 for engaging with external splines 312 ofmandrel 309 to prevent rotation of mandrel 309 within housings 307 and308. Cylindrical mandrel extension 309a contains one or more ports 320through the wall.

One or more pressure balancing ports 317 pass through the wall of upperhousing 307 and allow annular fluid under hydrostatic pressure tocommunicate with the upper face 318 of piston shoulder 311.

The buoyancy induced by hydrostatic pressure on the tool is equivalentto the hydrostatic pressure times the cross-sectional area. Thus, thebouyancy trying to push mandrel 309 upward in housings 307 and 308 isequivalent to the hydrostatic pressure times the crosssectional area ofmandrel 309 indicated by reference arrows as A The effective counterbalancing downward force arises from hydrostatic pressure acting onpiston face 318 and is calculated by multiplying hydrostatic pressuretimes the area of this face. Since this is a circular annular area it iscalculated as the area of the outer circle A minus the area of the innercircle A;,. For ideal balancing condition therefore (A A A To overcomefriction forces and other incidental factors, (A A should be slightlygreater than A or, as in this situation, a coil compression spring 310can be used to further bias against telescoping together of mandrelextension 309a and housing 308. In the outermost extended position ofmandrel extension 309a in housing 308, ports 306 are lined up verticallywith ports 320. In case rotation has occurred and lateral misalignmentof the two sets of ports occurs, an annular groove 319 is located aroundthe exterior of extension 309a to intersect all of ports 320 and providecontinuous fluid communication between the two sets of ports regardlessof horizontal rotation.

Lower housing 308 has seals 321 therein to seal against mandrelextension 309a and prevent fluid communication therebetween. Upperadapter 301 has internal seals 322 to seal against mandrel 309, andmandrel extension 309a has external seals 323 above and below ports 320to prevent fluid communication between mandrel extension 3090 and lowerhousing 308 around the port area.

The void areas between seals 314 and seals 321 are initially atatmospheric pressure and therefore allow a pressure differential to formacross piston 311 from hydrostatic pressure acting on piston face 318.Atmospheric pressure has access to these areas through ports 324 inmandrel 309. The void spaces between seals 321 and seals 323 are athydrostatic pressure from fluid entering one or more ports 391 in thewall of lower housing 308. Circular seal 325 is located between theupper and lower housings to prevent fluid leakage therebetween.

Below assembly 305 is located the upper inert gas chamber floatingpiston assembly 326 having two slidable floating pistons 327 and 328located therein. These two pistons are annular cylinders each havinginternal and external seal means 329. The piston cham ber is formed bycylindrical external housing member 330 which is fixedly attached to thelower end of mandrel extension 309a. Located concentrically withinhousing 330 and pistons 327 and 328 is a cylindrical uppermost innerbarrel 331 which sealingly engages mandrel extension 309a through seals332a and sealingly engages an orifice member 333 through seals 33212 toform a fluid tight chamber 334 around pistons 327 and 328.

Annular fluid access to chamber 334 is accomplished through ports 306and 320. A fluid cushion of oil 335 is maintained between pistons 327and 328 and held there by seals 329. Below the lower piston 328 is aninert gas such as nitrogen compressed under predetermined pressure.

Upper orifice member 333 is a cylindrical extension of housing 330having a reduced inner diameter forming an inward extending thickersection 333a. The thicker wall area serves to provide material throughwhich pass one or more orifice channels 336 communieating with lower gaschamber 337. Member 333 also has an inner shoulder 333b on which isseated inner barrel 331 and an upper intermediate inner barrel 338.Seals 339 prevent fluid communication between the orifice member 333 andhousing members 330 and 340.

Upper intermediate barrel 338 is sealingly engaged with upper orificemember 333 and a lower orifice member 343 by seal means 341a and 34lbrespectively.

Lower orifice member 343 is similar in construction to upper member 333and has one or more orifice channels 342 communicating lower gas chamber337 with the inert gas filler chamber 344.

It should be noted that uniform sections of chambers 334 and 337 havebeen broken out in order to shorten the drawings and facilitateunderstanding of the invention.

Gas filler chamber 344 is formed by an outer housing connector 345having a cylindrical configuration, and a lower intermediate innerbarrel 346. In the annular space between connector 345 and barrel 346 isa valve piston 347. Connector 345, piston 347 and barrel 346 cooperateto provide an inert gas filler assembly 353 for the apparatus. Connector345 has a gas filler port 348 and a pump actuating port 349. Piston 347is an annular sleeve type piston concentrically and slidably locatedbetween housing 345 and barrel 346. It has an enlarged diameter 351 atthe top containing circular seals 350, and a lesser diameter section 352comprising the lower approximately two-thirds of the piece.

The enlarged end 351 acts as a differential pressure area so that whenan actuating fluid or quasi fluid such as oil or grease is pumped underpressure through port 349 a resultant force upward will be applied onthe piston.

in the position shown, the filler valve assembly 353 is in a closedposition. Lower section 352 of the piston covers gas filler port 348 andcircular seals 354a and 354b above and below the port prevent leakage ofthe inert gas between the piston and the housing. When it is desirableto open the filler port to either add more inert gas or to drain inertgas, plug 355, which is threadedly secured in actuating port 349, isremoved and fluidic pressure is applied through the port to pistonshoulder 351. A convenient method of applying this pressure is by meansof a common grease gun, such as mechanics use, with an attachment forconnecting into port 349. Upon application of sufficient pressure acrossdifferential pressure area 351, piston 347 will move upward in responseto the hydraulic force on it. This will move seals 354b upward pastfiller port 348 until the lower end of the piston clears the port. Theinert gas can then be inserted into the port whereupon it flows to thevarious chambers in the tool. Piston 347 has a sufficiently large innerdiameter to allow the inert gas to flow between the piston and the innerbarrel 346.

When filling is completed, pressure on the actuating fluid is releasedat port 349 and the internal pressure of the inert gas which has beeninjected into the tool will force piston 347 back downward, closing offand sealing the filler port 348 by locating seals 354a and 354]: aboveand below the port.

Plug 355 can then be replaced in pumping port 349 to protect that portagainst sediment and well fluids and a similar plug 356 can be placed inthe filler port 348 to likewise protect it and further seal it offagainst gas leakage. it should be noted that the smallest inner diameterof housing connector 345 at 357 is large enough to allow the inert gasto pass downward between the connector and inner barrel 346.

Located immediately below housing connector 345 is shuttle valveassembly 360. This comprises a sliding cylindridal piston mandrel 358concentrically located within housing member 359, which is attached tohousing connector 345, with piston mandrel 358 encircling inner barrel346. Piston mandrel 358 is a cylindrical sleeve having an upper skirt358a and a lower skirt 3580 divided by an annular piston shoulder 3581:.Mandrel 358 has sufficiently large inner diameter throughout to providea flow space between it and inner barrel 346.

Located concentrically around upper skirt 358a is an upper cylindricalsleeve spacer 361 to limit upward travel of mandrel 358 by abutment withlower end of housing connector 345 and shoulder 358b of mandrel 358.Spacer 361 has seals 362a and 362k on its outer and inner surfaces toseal against housing 359 and mandrel 358 respectively. Lower cylindricalspacer sleeve 363 is located below piston shoulder 358b, encirclinglower skirt 3580, and having seals 3630 on its exterior and 363b on itsinterior surfaces to seal against housing 359 and mandrel skirt 3580respectively. Mandrel shoulder 358b has circular seals 358d thereon toseal against housing member 359. Lower spacer sleeve 363 limits downwardmovement of mandrel 358 by abutment with shoulder 358!) and innerhousing extension 364 which is concentrically located inside housingmember 359, and indirectly attached thereto by means of connectingmember 365. Extension 364 is a cylindrical sleeve type member having anupper skirt portion 364a with enlarged inner diameter to accomodate thelower end of mandrel skirt 3586, a stepped inner shoulder 36% toaccommodate the lower end of inner barrel 346, and inner ridge 364C tolimit downward movement of the inner barrel.

Extension 364 has seals 366a to seal against housing 359, seals 366b and366C to seal against mandrel skirt 358C, and seals 366d to seal againstinner barrel 346.

Housing 359 has a pump-open port 367a and a pump-closed port 367bthrough the wall thereof communicating with the inner mandrel 358 andspacer sleeves 361 and 363. When not in use, these two ports are filledwith protector plugs 368a and 368b respectively.

Mandrel 358 has a relief port 369a and communica' tion port 36% throughthe wall of skirt 3580. ln the open position, as shown in FIG. 3e, port36% aligns vertically with port 370a and annular groove 3701) whichpasses circumferentially around the inner surface of extension 364intersecting port 370a. This alignment allows communication of inert gasfrom the upper part of the tool, through the space 371a between mandrel358 and barrel 346 to the lower part of the tool via the annular space371b between housing member 359 and inner housing extension 364.

If it becomes desirable to remove the upper portion of power section 30from the lower portion, the connecting member 365 may be detached fromhousing member 359 and extension 364 by unscrewing the threadstherebetween. To prevent loss of the inert gas held in the upperportion, mandrel 358 is moved downward to close ports 36% and 370a offfrom one another. This is accomplished by removing plug 368b from port367b and attaching a fluid pressure means, such as a common grease gun,to the port 367b and applying pressure thereto. This pressure willoperate on piston shoulder 358b to force it downward until abutment ofspacer sleeve 363 on extension 364 occurs. Upper spacer 361 moves upwardin response to the fluidic pressure. Lower skirt 358c moves down acrossport 370a and groove 37% thereby blanking them off, and seals 366b and366C prevent any leakage along skirt 358c through port 370a. In theclosed position, the mandrel 358 is in a balanced position and will beheld closed by seal friction so that the pressure source can be removedand protector plug 368b replaced in port 367b. When it becomes desirableto reconnect the inert gas supply from the upper portion of the tool tothe lower portion, for instance after the lower portion has beenreattached to the upper portion, both plugs 368a and 368b are removedand a pressure source is connected to opening port 367a. When pressureis applied to the port it works against piston 358b to move mandrel 358back to its uppermost position whereupon ports 36% and 370a arerealigned and communication is achieved therethrough. Plug 368b isremoved to prevent back-pressure buildup above piston 35% due to fluidwhich normally would be trapped there were port 367b not opened.

Port 369a in skirt 358b is provided to allow inert gas to drain frombeneath lower spacer 363 and piston shoulder 358b when the mandrel ismoved downward to close the valve assembly. This prevents a gas trapfrom forming below the mandrel and allows easier downward movementthereof.

Immediately below housing connecting member 365 is the lower floatingpiston assembly comprising an external housing member 372 attached toconnecting member 365 and being a cylindrical tubular piece. Locatedconcentrically within housing 372 is a floating annular piston sleeve373 having external seals 373a and internal seals 373b located thereon.Lowermost inner barrel 374 is an elongated cylindrical tubular mandrellocated concentrically within connecting member 365 and piston 373 andsealingly engaged with member 365 by seals 374a.

Inert gas which passes through ports 36%, 370a, and annular space 371b,is communicated to lower piston chamber 375a through port 376 inconnecting member 365 and into annular space 376a between member 365 andinner barrel 374. Piston 373 provides a sealing barrier between theinert gas in chamber 375a and the oil cushion in chamber 375b. Seals373a provide sealing engagement with the interior surface of housing 372and seals 373b provide sealing engagement with inner barrel 374.

Located below chamber 375b is an inner annular shoulder 372a in housing372 through which passes an oil filler port 372b having a removable plugtherein. An annular passage 377a communicates from chamber 375b to aninner annular recess 377b in shoulder 372a. An impedance metering rodchannel 3770 communicates from recess 37712 to metering mandrel 378having therein an axial orifice 378a opening up into spring chamber 379.Metering rod 380 is located within channel 377s to provide hydraulicimpedance to oil flow therethrough.

Diametrically opposite channel 377C in shoulder 372a is relief bypasschannel 381 shown in dashed lines, having a ball and spring type checkvalve assembly 382 in the spring chamber end thereof and communicatingwith annular recess 377b. Furthermore, annular shoulder 372a contains aninner annular recessed portion 372c about inner barrel 374, which is incommunication with a second filler plug 381a.

Seals 374b between shoulder 372a and barrel 374 prevent fluid leakagebetween these two elements. Spring chamber 379 is formed by meteringmandrel 378 in conjunction with a lower external cylindrical housing 383and cylindrical bottom adapter 384 attached to housing 383. The innerwall of spring chamber 379 comprises inner barrel 374 to which isattached power piston 385 and cylindrical tubular sampler pull coupler386. Barrel 374, power piston 385, and coupler 386 move as a single unitin sliding relationship inside external housing members 365, 372, 383,and cylindrical adapter 384. Coil spring 387 is disposed around barrel374 and between metering mandrel 378 and power piston 385, and works incomparison to bias the power piston towards its lowermost position asshown in FIG. 3h. Power piston 385 is a cylindrical sleeve having araised annular piston shoulder 385b, seals 385a and lower skirt 3850.

Power piston seals 385a on piston shoulder 385b provide sealingengagement with inner wall of housing 383, and seals 384a providesealing engagement between pull coupler 386 and adapter 384.

Pull coupler 386 and adapter 384 have threads 388 and 389 thereon toallow attachment of the separable sampler shown in FIGS. 4a through 4d.

Housing 383 has one or more annulus pressure actuating ports 390 throughthe wall thereof to communicate fluid pressure from the annulus area tothe power piston shoulder 38512 which acts as a differential pressurearea between the annulus pressure and a the internal inertgas pressure.

OPERATION OF THE POWER SECTION The power section illustrated in FIGS. 3athrough 3g is charged with a relatively low pressure of inert gas inchamber 334 and is then placed in the testing string by threading theupper end in FIG. 3a into the conduit or next upper tool in the string.The sampler section 40 is attached to the power section at the lower endand the remainder of the test string, including a packer mechanism, isattached to the lower end of the sampler section.

While the string is being lowered into the hole, the weight of thestring below the power section applies tension to the power sectionwhich tension telescopes the port valve assembly 305 into its mostextended position as shown in FIGS. 3a and 3b.

As the string is lowered, any bouyancy arising from the fluid in thewell which naturally tends to push the string back upward, iscounterbalanced by allowing hydrostatic fluid pressure to react throughports 317 and down against differential pressure area 318.

When the string is in the correct position in the well, the packer isexpanded against the borehole by known conventional methods therebyanchoring the lower end of the string against further movement. Then thestring is allowed to move further down by the weight of the upperstring, thereby telescoping assembly 305 inward which is a result ofhousings 307 and 308 moving downward over internal mandrel 309.

During the descent of the power section in the borehole, because of thetension on the assembly 305, annulus pressure access ports 306 and 320remain in vertical alignment with peripheral groove 319 guaranteeingfluid communication therebetween. Annulus pressure increasesproportionately to the depth of the tool in the well fluid. Theincreasing annulus pressure arising with the descent of the tool actsthrough ports 306 and 320 a and down between barrel 331 and mandrelextension 309a to upper piston 327. A hydraulic fluid is located betweenpistons 327- and 328 to provide a better seal between the annulus fluidabove piston 327 and the inert gas below piston 328. The annuluspressure acting on piston 327 is transferred via the hydraulic fluid topiston 328 which moves downward with piston 327 to compress the inertgas in chamber 334. This process occurs until the tool reachesbottomhole whereupon the inert gas will then be at hydrostatic pressureof the annulus fluid.

When the string reaches location, the above mentioned packer is set andweight is set down on the packer thereby moving housing 308 downwardover mandrel extension 309a, moving ports 306 out of alignment withports 320 and sealing off the inert gas cham- 13 her from furtherhydrostatic pressure of the annulus fluid.

At this point the power section may be remotely actuated by applyingfluidic pressure to the annulus fluid, which increased pressure actsthrough ports 390 and upward against power piston shoulder 385b therebymoving piston 385 upward while compressing coil spring 387 and inert gasin chamber 375a through abutment with hydraulic fluid between piston 385and floating piston 373. Upon release of the applied pressure on theannulus fluid, the biasing action of spring 387 and inert gas abovepiston 373 acts on piston 385 moving it back downward into its at-restposition.

Movement upward of piston 385 is transferred to the sampler section 40by way of pull coupler 386 which is fixedly secured to piston 385 and tothe pull coupler connector section 438 of the sampler section.

When it is desirable to remove the tool from the hole, applied pressureon the annulus fluid is released, the packer is released, and the stringis pulled upward. This once again extends port valve assembly 305,aligning ports 306 with ports 320, and allows the supplementalhydrostatic pressure acting on pistons 327 and 328 to drain off as thetool comes out of the hole and hydrostatic pressure of the annulus fluiddecreases in proportion to the decreasing tool depth.

THE SAMPLER SECTION The separable sampler 40 is shown in detail in FIGS.4a through 4d. FIG. 4a shows in phantom the lower end of the powersection 30 and illustrates how the power section 30 and sampler section40 are joined.

Sampler section 40 consists basically of a stationary housing assembly401, a pull mandrel assembly 402 and a valve mandrel assembly 403.

Housing assembly 401 consists of a cylindrical tubular upper externalhousing 404, intermediate housing 405, and lower housing 406, as well asthreaded assembly connector collars 407 and 408, upper and lower drainvalve heads 409 and 410, and upper and lower flow port sleeves 411 and412.

The three external housings 404, 405 and 406 are joined together bymeans of connector collars 407 and 408 to form a substantiallycylindrical elongated tubular member.

Upper connector collar 407 has an inner threaded section 413 whichreceives upper flow port sleeve 411 in fixedly attached relationshiptherewith. Sleeve 411 is a tubular, cylindrical, slotted sleeve having alongitudinally extending slot 414 through the wall thereof. Also passingthrough the wall of sleeves 411 and 412 are two sets of one or more flowports 415 and 457. Circular seals 416 are located in annular recesses inthe internal bore wall of sleeve 411. F ixedly attached to the upper endof sleeve 411 is the upper drain valve head 409 which is a relativelythick-walled tubular member having a large exit port 417 passing throughthe wall thereof. Head 409 has a restricted axial bore 418 pass inglongitudinally therethrough. The inner wall of bore 418 has annular sealmeans 419 located in recesses therein.

A solid cylindrical plug means 420 is sealingly engaged within bore 418of head 409 and threadedly held therein by annular adapter 421.

Upper end 422 of plug 420 is polygonal-shaped to allow a wrench to beapplied thereto in order to rotate plug 420 in head 409.Counterclockwise rotation of plug 420 results in axial movement outwardof plug 420 in head 409 and sufficient movement outward will result inthe lower end 423 of plug 420 clearing exit port 417 so that fluidwithin the central bore of sampler section 40 may flow outward throughport 417. Seals 419 and 419a prevent fluid flow between plug 420 and theinner bore wall of head 409 until plug end 423 moves outward past port417.

The construction and orientation of the lower flow port sleeve 412,lower drain valve head 410, and lower head plug 424 are very similar tothat of the upper port sleeve 411, upper head 409, and plug 420 asdescribed above, but in an inverted orientation thereto. The oper'ation, function, and purpose of these lower elements are substantiallyidentical to the aforementioned upper ones. Plug 424 serves as a valvemember to cover or uncover exit port 425 in lower head 410 by threadedconjunction with annular adapter 426. Plug 424 has a polygonal head 427and engages seal means 428 above port 425 in the inner bore of head 410.Seals 429 in plug 424 provide sealing engagement with plug 424 belowport 425.

In addition, lower head 410 has fixedly attached at the upper endthereof, a tubular lock-closed sleeve 430 with biasing spring 431located thereon in conjunction with one or more prop arms 432 swingablyattached to sleeve 430 at their lower ends. The function and purpose ofsleeve 430, biasing spring 431, and prop arms 432 will be moreparticularly described later in conjunction with the operation of thesampler section. Sleeve 430, in conjunction with sleeve 412, serves toform an extended annular slip space 433 therebetween.

The pull mandrel assembly 402 comprises an elongated pull mandrel yoke402a having a cylindrical limit-stop sleeve 434 frangibly attachedexteriorly thereto by shear pins 441 in telescopic arrangement. Pullmandrel assembly 402 is slidably arranged concentrically within upperexternal housing 404 and has a lower expanded elongated yoke section 435passing slidably and concentrically in relatively close relationshipbetween housing 404, head 409 and sleeve 411. Located above yoke section435 is necked tubular section 436 having a reduced diameter and one ormore ports 437 through the wall thereof. Integrally attached to section436 is the pull coupler connector section 438 having an intermediatediameter and having internal threads 439 therein for attaching to thepower section pull coupler 386. Likewise, upper housing 404 has internalthreads 440 at its upper end for engaging adapter 384 of the powersection 30.

Mandrel yoke 402a and limit-stop sleeve 434 are located so that yoke402a has approximately two inches of travel from its lowermost positionas illustrated, to its uppermost position whereupon limit-stop sleeve434 is abuttingly engaged with the lowermost end of adapter 384 thereby,under normal operating conditions, preventing any further upwardmovement of the mandrel assembly 402 within housing 404.

Valve mandrel 403 consists of an elongated, tubular, cylindrical piecehaving enlarged upper section 442 and lower section 443 joined togetherby attachment to a reduced-diameter, solid central section 444.

Near the lower end of section 442 and near the upper end of section 443are short, tapered frusto-conical wall sections 445 and 446respectively, having a plurality of flow ports therethrough numbered 447and 448 respectively.

Upper section 442 is slidably located within collar 407 and sleeve 411and sealingly engaged therewith and has an inner bore 449 communicatingthrough ports 447 to an annular chamber area 450 formed by theconcentric arrangement of the external housing 405 and the reducedcentral section 444. Chamber 450 also communicates with the inner bore455 of lower section 443 through ports 448 in conical wall 446.

One or more linkage pins 451 are securedly imbedded in the wall of uppersection 442 and pass radially through one or more slots 414 in the upperflow port sleeve 411. Pins 451 extend far enough through slots 414 to besecuredly engaged with the arms of pull mandrel yoke 402a. Slots 414 andpins 451 are designed to allow pins 451 to slide freely through slots414 in a longitudinal, axial direction yet prevent any significantangular rotation therein.

Furthermore, it should be noted that upper and lower sections 442 and443 of valve mandrel 403 have a plurality of ports 453 and 454respectively through the wall thereof, circumferentially spaced thereon,and arranged to communicate with annular grooves 452 and 456 out in theinner bore wall of flow port sleeves 411 and 412. Grooves 452 and 456are located so that they intersect flow ports 415 and 457 to allow fluidcommunication therethrough when ports 453 and 454 are axially alignedtherewith, even though ports 453 may be peripherally non-aligned withports 415, and ports 454 may be peripherally non-aligned with ports 457.

In the lowermost position of valve mandrel 403, with respect to housingassembly 401, ports 415 and 457 are sealed off from bores 409 and 455and chamber 450 by the blocking position of the upper and lower sectionsof the valve mandrel 403.

When mandrel 403 moves to its uppermost position, ports 415 and 457 arealigned axially with ports 453 and 454 respectively. Fluid flow is thenpossible throughout the entire length of the apparatus by flowingthrough inner bore 458 of the pull mandrel assembly, through ports 437,between the arms of yoke 402a, through ports 415 and 453, through bore449, ports 447, bore 450, ports 448, bore 455, and through ports 454 and457 into bore 459 which communicates with the lower part of the stringthrough well conduit attached to the lower end 460 of housing 406.

FIG. 5 illustrates the construction of pull mandrel yoke 402a having oneor more arms 461 which pass downward outside of sleeve 411 and arepinned to valve mandrel 403 by pins 451. The preferred embodiment hereinutilizes two yoke arms diametrically opposed one from the other tothereby provide sufficient pull strength which is balanced across thediameter of the yoke, and also allow the greatest open area to fluidflow between the yoke arms.

Additionally, a spool type relief valve 462 is located through the lowerend 460 of lower housing 406. This valve is designed to allow theoperator to drain off high pressure well fluids and/or gases which maybecome trapped in bore 459 between the closed sampler chambers 449, 450,and 455 and the closed valve below the sampling mechanism 25.

Valve 462 consists of a cylindrical outer housing 463 having two or moreports 464 through the wall thereof, with a threaded spool assembly 465sealingly engaged therein. In the illustrated position the valve isclosed but does allow flow around it along bore 459. After the samplerhas been filled and closed and it is desired to drain off the hazardousfluids trapped in bore 459, a conduit (not shown) can be threadedlyattached in threaded opening 466 of housing end 460 and the polygonalupper end 467 of spool assembly 465 can be turned counterclockwise witha common wrench. This rotates the spool outward by action of threads 468on the spool with threads 470 on annular adapter 469 located securely inhousing end 460. Continued rotation of spool assembly 465 will move theend 471 of the spool past ports 464 and allow the trapped fluid to flowtherethrough and out threaded opening 466 into the drain conduit (notshown).

Operation of the separable sampler section 40 occurs in the followingmanner. A sufficient annulus pressure increase acting on the powersection 30 of the sampler mechanism 25 results in an upward movement ofpull coupler 386. In the orientation of the sampler section 40 asillustrated, the sampler chamber is initially closed to fluid flowtherethrough and no flow can occur through the conduit string.

Upward movement of the pull coupler 386 pulls the pull mandrel assembly402 upward with it until limit stop sleeve 434 abuts the bottom end ofadapter 384. In this position the sampler is fully opened and flow canoccur therethrough and throughout the conduit string. The sampler can beheld open by continuous application of the actuating pressure on theannulus fluid. In the open position, pull mandrel assembly 402, workingthrough pins 451, have pulled the valve mandrel assembly 403 upwarduntil ports 415 are aligned with ports 453 which simultaneously alignsports 457 with ports 454, which alignment provides an open flow paththrough the sampler as previously described When it is desired to ceaseflow tests and begin pressure buildup tests or trap a sample, actuatingpressure is released from the annular fluid which allows the inert gasand spring biasing means in the power section to move the pull coupler386 back to its initial position thereby moving the valve mandrelassembly 403 back downward, closing off flow ports 415 and 457.

A sample of the well-fluid which was flowing through the open samplerwill automatically be trapped in bores 449 and 455 and in annularchamber 450.

After the desired tests have been completed and the sample has beentrapped, the test string is removed from the hole and the separablesampler section 40 may be removed from the power section and replaced byan empty one if desired. Before the sampler is removed from the string,though, it is often desirable to remove trapped formation fluids fromthe void area below the sample chamber which can be accomplished by theuse of a conduit attached to threaded opening 466 and manipulation ofspool valve 462 as previously described.

After the sampler section 40 is removed from the string it can beshipped to the lab for testing. At the lab, the upper and lower externalhousings 404 and 406 can be unscrewed from the apparatus and set asideto expose the drain ports 417 and 425. Only one such drain port need beexposed although both can be if so de sired. The sample is removed fromthe sample chamber by attaching a drain conduit (not shown) into theenlarged threaded portion 472 or 473 of drain ports 417 or 425respectively.

Then threaded plug 420 or plug 424 is screwed out of the end having thedrain conduit connected therein until the end of the plug clears thedrain port 417 or 17 425, whichever the case may be, and the trappedfluid is allowed to exit from the sample chamber.

In addition to providing structural integrity of the sampler section aswell as serving to connect the sampler to the power section and theconduit string, upper and lower housings 404 and 406 also serve asprotective shields over the sample drain port assemblies duringtransportation of the sampler from the field to the lab.

As previously noted, the sampler incorporates a further safety featuredesigned to move the sampler section into a lock-closed position shouldthe well suddenly become overpressured and threaten to blow out throughthe annulus.

The sudden overpressuring of the annulus fluid will act upon the powersection to provide an increasingly greater upward pulling force on thepull mandrel assembly 402 until finally, at a predetermined maximumannulus pressure, shear pins 441 in limit stop sleeve 434 will besheared thereby allowing the pull mandrel yoke 4020 to pull the valvemandrel 403 an additional distance upward thereby pulling the bottom end474 of the mandrel clear of the hinged prop arms 432. At this instantthe biasing springs 431 force arms 432 radially outward behind end 474of the valve mandrel thereby preventing any reverse movement of themandrel back downward.

This additional increment of upward movement of valve mandrel 403 uponshearing of pins 441 results in moving of ports 453 and 454 out ofalignment with ports 415 and 457 thereby closing off any further flowthrough the sampler. Prop arms 432 serve to keep the valve mandrel inthis upward lock-closed position. Seals 475 and 476 located in annularrecesses in the outer surface of valve mandrel lower section 443 arelocated so that in the lock-closed position they straddle the flow port457 and prevent fluid leakage thereby. Seals 477 and 478 located onlower section 443 above ports 454 serve to prevent fluid leakage therebywhen the sampler is in its initially closed and open-flowingorientations.

SUMMARY AND ADVANTAGES OF THE APPARATUS The sampler mechanism disclosedherein is particularly advantageous for use in wells wherein it ishighly desirable to operate tools in the string without resorting to anyphysical manipulation of the drillpipe such as reciprocation orrotation.

This mechanism provides an annulus pressure operated sampler which isvery versatile in that it can be utilized in deep hot holes where theexact pressure and downhole temperature are not shown. By the use ofthis tool these conditions need be determined only approximately.

Furthermore, the sampler mechanism does not require a high pressureinert gas charge in the spring biasing chamber to overcome the highhydrostatic pressure at bottomhole but instead can be charged atrelative low pressures at the surface and then utilizes the hydrostaticpressure as it goes in the hole to supplement the inert gas chamberpressure and serve as a biasingclosed means.

In addition, this mechanism employs a safety sampler that is separablefrom the power section and which can be opened and closed an indefinitenumber of times by actuation of the power section. The sampler can beremoved from the string and sent to the lab with the sample intact andanother dry sampler inserted in its place and the test string returnedto the hole or taken to another job right away.

Use of this mechanism obivates the need for a power section for eachsampler and allows a testing crew to operate almost indefinitely withonly one power section and as many sampler sections as needed.

Also the sampler section of this mechanism provides an easily accessibleyet protectively shielded drain port mechanism. It also features alock-closed safety feature that closes and locks the sampler flow portswhen an undesirable high pressure condition arises in the annulus.

The sampler section provides a means of draining off formation fluidstrapped between the sampler and tools below it in the string. Thisprovides a clean spill-free access and method to drain these usuallyflammable and always dirty contaminants.

Although a specific preferred embodiment of the present invention hasbeen described in the detailed description above, the description is notintended to limit the invention to the particular forms or embodimentsdisclosed herein, since they are to be recognized as illustrative ratherthan restrictive and it will be obvious to those skilled in the art thatthe invention is not so limited. For example, it would be possible toutilize a varying number of floating pistons in the power section 30, ordifferent spring biasing means than those disclosed as coil springs.Where the porting is disclosed as allowing the supplementary hydrostaticpressure to enter near the top of the power section and actuatingannulus pressure to enter near the lower end of the power section, it isobvious that one could reverse the orientation of various tool parts andobtain a reversal of the porting arrangement disclosed herein. Theinvention is declared to cover all changes and modifications of thespecific example of the invention herein disclosed for purposes ofillustration, which do not constitute departures from the spirit andscope of the invention.

What is claimed is:

1. Oil well sampling apparatus for placement in a testing string,comprising:

power section means arranged to receive applied fluidic pressure onfluids between the test string and the well casing and convert saidpressure applications into sampler actuating movement in the teststring; and

sampler means arranged to be attached to said power section means andreceive said actuating movements thereby controlling fluid flow throughthe test string and capable of trapping a sample of the fluid therein; v

said power section means further comprising:

a substantially cylindrical outer housing assembly having a boretherethrough;

an inner barrel assembly concentrically located within said housingassembly and forming a plurality of annular chambers therebetween, saidinner barrel assembly having a substantially open unrestricted boretherethrough;

a valve sleeve assembly slidably located on said housing assembly andhaving a plurality of ports through the wall thereof, some of said portsbeing capable of fluidically communicating with a plurality of portsthrough the wall of said housing;

said sleeve assembly arranged to be pressure balanced against buoyancyof said testing string and said sleeve assembly further adapted to movein response to reciprocation of said testing string to align some ofsaid ports in said sleeve assembly with said ports in said housing inone position of said sleeve assembly; and in a second position of saidsleeve assembly to prevent flow through said housing assembly ports;supplemental pressure annular floating piston means located in sealingengagement between said housing assembly and said inner barrel assemblyand having fluid communication with said housing assembly ports, saidpiston means capable of sliding movement between said housing assemblyand said barrel assembly; spring biasing means located between saidouter housing assembly and said inner barrel assembly blow saidsupplemental pressure annular floating piston means and arranged inspringing engagement therewith; said spring biasing means comprising aninert gas chamber; second annular floating piston means slidably andsealingly located within said chamber; pressurized inert gas within saidchamber between said supplemental piston means and said second annularfloating piston means; and mechanical spring means abutting said secondannular piston means; power piston means slidably and concentricallylocated within said housing assembly in abutting relationship with saidspring biasing means and reacting in conjunction with said secondannular floating piston means by way of hydraulic fluid sealinglyemplaced between said power piston means and said second annularfloating piston means; said power piston means arranged to receiveannulus fluid through a second plurality of ports through the wall ofsaid housing assembly and adapted to react in longitudinal movementagainst said spring biasing means in response to fluidic pressureapplied to said annulus fluid, said power piston means having adifferential pressure area thereon; and pull mandrel means locatedslidably within said housing assembly and arranged to move in responseto longitudinal movement of said power piston means; said pull mandrelmeans adapted to engage said sampler means and transfer longitudinalmovements thereto. 2. The sampling apparatus of claim 1 furthercomprising:

inert gas filler valve means located in said housing assembly; inert gaschamber isolation valve means located in said housing; hydraulicimpedance means located in said housing between said second annularfloating piston means and said power piston means in said hydraulicfluid and arranged to dampen movements of said power piston means; andcheck valve means in communication with said hydraulic fluid and locatedin parallel with said impedance means and adapted to bypass saidimpedance means upon longitudinal movement of said power piston means inresponse to said spring biasing means.

v 3. The sampling apparatus of claim 1 wherein said sampler meansfurther comprises:

a cylindrical external sampler housing assembly having a bore thereinand adapted to be securedly attached to said power section housingassembly;

an upper, inner housing extension member fixedly attached to theinterior of said external sampler housing, located concentricallytherein, and having an open axial bore therethrough;

a lower inner housing extension member fixedly attached to the interiorof said external sampler housing located concentrically therein, coaxialwith said upper extension member, and having an open axial boretherethrough;

valve mandrel means slidably located within said upper and lowerextension members and said sam pler housing assembly and forming asample chamber therein;

valve coupler means located concentrically within said sampler housing,attached to said valve mandrel means, and adapted to be securedlyengaged with said pull mandrel means in said power section means;

first port means in said valve mandrel means comprising two sets ofports through the wall thereof;

second port means through the wall of said upper extension member andarranged to communicate with one set of ports in said first port meansin one position of said valve mandrel means within said housingassembly; and

third port means through the wall of said lower extension member andarranged to communicate with the other set of ports in said first portmeans simultaneously with said communication between said second portmeans and said first port means.

4. The sampling apparatus of claim 3 further comprising:

drain valve means in said sample chamber, said drain valve meansincluding: a drain port through the wall of said upper extension member;plug means threadedly engaged in said upper extension member, alignedcoaxially with said upper extension member, and threadedly engaged inthe bore thereof so as to block said drain port in a first positionthereof; said plug means further adapted to be selectively moved out ofblocking engagement with said drain port; and

said drain port having drain conduit attachment means therein.

5. The sampling apparatus of claim 3 further comprising:

safety lock-closed means, said lock-closed means including: limit-stopsleeve means frangibly attached to said valve coupler means and arrangedto abut said power section means in a first, open position of said valvemandrel means;

a concentric inner sleeve attached to said lower extension memberlocated concentrically within said valve mandrel means;

a plurality of prop-arms hingedly attached to said inner sleeve betweensaid inner sleeve and said valve mandrel means and arranged to swing outin propping relationship below said valve mandrel means upon shearing ofsaid limit-stop sleeve means in response to extreme upward movement ofsaid valve coupler means; and spring actuation means between saidprop-arms and said inner sleeve arranged to move said proparms out intopropping relationship below said valve mandrel means upon sufficientmovement upwards of said valve mandrel means to clear said springactuation means. 6. A sampler apparatus for use in a test string in anoil well comprising:

a power section having a central bore therethrough, 15

which comprises;

a piston responsive to fluid pressure in the annulus exterior to thetest string such that increases in said annulus pressure will move saidpiston in a first longitudinal direction,

means engaged with said piston for biasing said piston in order thatsaid piston will move in a second longitudinal direction opposite tosaid first direction when said annulus pressure increases are removed,

means for supplementing said biasing means with hydrostatic pressure inthe annulus as the apparatus is lowered into the well, and

means having an open position and a closed position for selectivelyisolating said supplementing means such that hydrostatic pressure in theannulus while said isolating means is in the open position will actuatesaid supplementing means, and increases in the annulus pressuresubsequent to the closing of said isolating means will move said pistonin the first direction against said biasing means, and

a sampler section removably attached to said power section and having acentral bore therethrough communicating with said central bore of saidpower section, which comprises;

means removably attached to said piston for transferring movements ofsaid piston, and

two valves in said sampler section spaced apart to form a sample chambertherebetween, both valves being actuated by said movement transferringmeans to open when said piston moves in the first longitudinal directionthereby allowing formation fluid to flow through said central bores, andto close when said piston moves in the second longitudinal directionthereby trapping a sample of formation fluid in said sample chamber,

said valves further having a fail safe position wherein said valves areclosed when the annulus pressure increases above a predetermined levelthereby moving said piston and said valves by the action of saidmovementtransferring means in the first longitudinal direction to a fail safeposition.

7. The apparatus of claim 6 wherein said piston comprises an annulartubular piston arranged within said power section to abut said biasingmeans, said piston 6 attached to said movement transferring means andadapted to receive said applications of increased annulus pressure.

8. The apparatus of claim 6 wherein said isolating means is remotelyshifted to the opened or closed position by manipulations of the teststring.

9. The apparatus of claim 6 wherein one valve ofsaid sampler sectioncontrols fluid communication between said sample chamber and saidcommunicating central bores through the sampler section and the powersection, wherein said second valve of said sampler section controlsfluid communication between said sample 10 chamber and the test string,and wherein said valves are actuated by said movement transferring meansto open and close simultaneously in response to longitudinal movementsof said piston.

10. The apparatus of claim 6 wherein said sampler comprises a means forlocking said valves in the closed fail safe position when said movementtransferring means has moved said valves to the fail safe position inresponse to movement of said piston under the influence of overpressurein the annulus.

11. The apparatus of claim 6 wherein said biasing means comprises apressured inert gas filled chamber forming an inert gas spring withinsaid power section arranged to bias against said piston as said pistonmoves in the first longitudinal direction.

12. The apparatus of claim 11 wherein said supplementing means comprisesa floating annular piston adajcent said inert gas spring and exposed onone side to the pressurized inert gas of said gas spring, and ex- 30posed on a second side to the hydrostatic pressure in said annulus, andfree to move in response to said hydrostatic pressure to furtherpressurize said inert gas.

13. The apparatus of claim 12 wherein said isolating means comprises avalve between said second side of said floating piston and said annuluswhich when open allows fluid communication between said floating pistonand said annulus, and when closed blocks fluid communication betweensaid floating piston and said annulus.

14. The apparatus of claim 12 wherein said floating annular pistoncomprises spaced apart, axially aligned sleeve pistons and oil locatedin the space between said sleeve pistons.

15. The apparatus of claim 11 wherein said biasing means furthercomprises a mechanical spring arranged to work in conjunction with saidinert gas spring to further bias said piston in said second longitudinaldirection.

16. The apparatus of claim 15 with said power section having a springchamber containing said mechanical spring between said piston and saidinert gas spring, said power section further comprising:

a fluid conduit communicating said spring chamber with said inert gasfilled chamber;

an oil cushion in said spring chamber wherein a portion of said oil isdisplaced from said spring chamber through said fluid conduit and intosaid gas filled chamber as said piston is moved in the firstlongitudinal direction; and

a floating annular piston slidably located in said inert gas tilledchamber exposed on one side to said pressurized inert gas and on asecond side to said displaced oil.

17. The apparatus of claim 16 wherein said fluid conduit containshydraulic impedance means for impeding the rate of oil displacement fromsaid spring chamber to said inert gas filled chamber to thereby dampen

1. Oil well sampling apparatus for placement in a testing string,comprising: power section means arranged to receive applied fluidicpressure on fluids between the test string and the well casing andconvert said pressure applications into sampler actuating movement inthe test string; and sampler means arranged to be attached to said powersection means and receive said actuating movements thereby controllingfluid flow through the test string and capable of trapping a sample ofthe fluid therein; said power section means further comprising: asubstantially cylindrical outer housing assembly having a boretherethrough; an inner barrel assembly concentrically located withinsaid housing assembly and forming a plurality of annular chamberstherebetween, said inner barrel assembly having a substantially openunrestricted bore therethrough; a valve sleeve assembly slidably locatedon said housing assembly and having a plurality of ports through thewall thereof, some of said ports being capable of fluidicallycommunicating with a plurality of ports through the wall of saidhousing; said sleeve assembly arranged to be pressure balanced againstbuoyancy of said testing string and said sleeve assembly further adaptedto move in response to reciprocation of said testing string to alignsome of said ports in said sleeve assembly with said ports in saidhousing in one position of said sleeve assembly; and in a secondposition of said sleeve assembly to prevent flow through said housingassembly ports; supplemental pressure annular floating piston meanslocated in sealing engagement between said housing assembly and saidinner barrel assembly and having fluid communication with said housingassembly ports, said piston means capable of sliding movement betweensaid housing assembly and said barrel assembly; spring biasing meanslocated between said outer housing assembly and said inner barrelassembly blow said supplemental pressure annular floating piston meansand arranged in springing engagement therewith; said spring biasingmeans comprising an inert gas chamber; second annular floating pistonmeans slidably and sealingly located within said chamber; pressuRizedinert gas within said chamber between said supplemental piston means andsaid second annular floating piston means; and mechanical spring meansabutting said second annular piston means; power piston means slidablyand concentrically located within said housing assembly in abuttingrelationship with said spring biasing means and reacting in conjunctionwith said second annular floating piston means by way of hydraulic fluidsealingly emplaced between said power piston means and said secondannular floating piston means; said power piston means arranged toreceive annulus fluid through a second plurality of ports through thewall of said housing assembly and adapted to react in longitudinalmovement against said spring biasing means in response to fluidicpressure applied to said annulus fluid, said power piston means having adifferential pressure area thereon; and pull mandrel means locatedslidably within said housing assembly and arranged to move in responseto longitudinal movement of said power piston means; said pull mandrelmeans adapted to engage said sampler means and transfer longitudinalmovements thereto.
 2. The sampling apparatus of claim 1 furthercomprising: inert gas filler valve means located in said housingassembly; inert gas chamber isolation valve means located in saidhousing; hydraulic impedance means located in said housing between saidsecond annular floating piston means and said power piston means in saidhydraulic fluid and arranged to dampen movements of said power pistonmeans; and check valve means in communication with said hydraulic fluidand located in parallel with said impedance means and adapted to bypasssaid impedance means upon longitudinal movement of said power pistonmeans in response to said spring biasing means.
 3. The samplingapparatus of claim 1 wherein said sampler means further comprises: acylindrical external sampler housing assembly having a bore therein andadapted to be securedly attached to said power section housing assembly;an upper, inner housing extension member fixedly attached to theinterior of said external sampler housing, located concentricallytherein, and having an open axial bore therethrough; a lower innerhousing extension member fixedly attached to the interior of saidexternal sampler housing located concentrically therein, coaxial withsaid upper extension member, and having an open axial bore therethrough;valve mandrel means slidably located within said upper and lowerextension members and said sampler housing assembly and forming a samplechamber therein; valve coupler means located concentrically within saidsampler housing, attached to said valve mandrel means, and adapted to besecuredly engaged with said pull mandrel means in said power sectionmeans; first port means in said valve mandrel means comprising two setsof ports through the wall thereof; second port means through the wall ofsaid upper extension member and arranged to communicate with one set ofports in said first port means in one position of said valve mandrelmeans within said housing assembly; and third port means through thewall of said lower extension member and arranged to communicate with theother set of ports in said first port means simultaneously with saidcommunication between said second port means and said first port means.4. The sampling apparatus of claim 3 further comprising: drain valvemeans in said sample chamber, said drain valve means including: a drainport through the wall of said upper extension member; plug meansthreadedly engaged in said upper extension member, aligned coaxiallywith said upper extension member, and threadedly engaged in the borethereof so as to block said drain port in a first position thereof; saidplug means further adapted to be selectively moved out of blockingengagement with said drain port; and said drain port having drainconduit attachment means therein.
 5. The sampling apparatus of claim 3further comprising: safety lock-closed means, said lock-closed meansincluding: limit-stop sleeve means frangibly attached to said valvecoupler means and arranged to abut said power section means in a first,open position of said valve mandrel means; a concentric inner sleeveattached to said lower extension member located concentrically withinsaid valve mandrel means; a plurality of prop-arms hingedly attached tosaid inner sleeve between said inner sleeve and said valve mandrel meansand arranged to swing out in propping relationship below said valvemandrel means upon shearing of said limit-stop sleeve means in responseto extreme upward movement of said valve coupler means; and springactuation means between said prop-arms and said inner sleeve arranged tomove said prop-arms out into propping relationship below said valvemandrel means upon sufficient movement upwards of said valve mandrelmeans to clear said spring actuation means.
 6. A sampler apparatus foruse in a test string in an oil well comprising: a power section having acentral bore therethrough, which comprises; a piston responsive to fluidpressure in the annulus exterior to the test string such that increasesin said annulus pressure will move said piston in a first longitudinaldirection, means engaged with said piston for biasing said piston inorder that said piston will move in a second longitudinal directionopposite to said first direction when said annulus pressure increasesare removed, means for supplementing said biasing means with hydrostaticpressure in the annulus as the apparatus is lowered into the well, andmeans having an open position and a closed position for selectivelyisolating said supplementing means such that hydrostatic pressure in theannulus while said isolating means is in the open position will actuatesaid supplementing means, and increases in the annulus pressuresubsequent to the closing of said isolating means will move said pistonin the first direction against said biasing means, and a sampler sectionremovably attached to said power section and having a central boretherethrough communicating with said central bore of said power section,which comprises; means removably attached to said piston fortransferring movements of said piston, and two valves in said samplersection spaced apart to form a sample chamber therebetween, both valvesbeing actuated by said movement transferring means to open when saidpiston moves in the first longitudinal direction thereby allowingformation fluid to flow through said central bores, and to close whensaid piston moves in the second longitudinal direction thereby trappinga sample of formation fluid in said sample chamber, said valves furtherhaving a fail safe position wherein said valves are closed when theannulus pressure increases above a predetermined level thereby movingsaid piston and said valves by the action of said movement transferringmeans in the first longitudinal direction to a fail safe position. 7.The apparatus of claim 6 wherein said piston comprises an annulartubular piston arranged within said power section to abut said biasingmeans, said piston attached to said movement transferring means andadapted to receive said applications of increased annulus pressure. 8.The apparatus of claim 6 wherein said isolating means is remotelyshifted to the opened or closed position by manipulations of the teststring.
 9. The apparatus of claim 6 wherein one valve of said samplersection controls fluid communication between said sample chamber andsaid communicating central bores through the sampler section and thepower section, wherein said second valve of said sampler sectioncontrols fluid communication between said sample chamber and the teststring, and wherein said valves are actuated by said movementtransferring means to open and close simultaneously in respoNse tolongitudinal movements of said piston.
 10. The apparatus of claim 6wherein said sampler comprises a means for locking said valves in theclosed fail safe position when said movement transferring means hasmoved said valves to the fail safe position in response to movement ofsaid piston under the influence of overpressure in the annulus.
 11. Theapparatus of claim 6 wherein said biasing means comprises a pressuredinert gas filled chamber forming an inert gas spring within said powersection arranged to bias against said piston as said piston moves in thefirst longitudinal direction.
 12. The apparatus of claim 11 wherein saidsupplementing means comprises a floating annular piston adajcent saidinert gas spring and exposed on one side to the pressurized inert gas ofsaid gas spring, and exposed on a second side to the hydrostaticpressure in said annulus, and free to move in response to saidhydrostatic pressure to further pressurize said inert gas.
 13. Theapparatus of claim 12 wherein said isolating means comprises a valvebetween said second side of said floating piston and said annulus whichwhen open allows fluid communication between said floating piston andsaid annulus, and when closed blocks fluid communication between saidfloating piston and said annulus.
 14. The apparatus of claim 12 whereinsaid floating annular piston comprises spaced apart, axially alignedsleeve pistons and oil located in the space between said sleeve pistons.15. The apparatus of claim 11 wherein said biasing means furthercomprises a mechanical spring arranged to work in conjunction with saidinert gas spring to further bias said piston in said second longitudinaldirection.
 16. The apparatus of claim 15 with said power section havinga spring chamber containing said mechanical spring between said pistonand said inert gas spring, said power section further comprising: afluid conduit communicating said spring chamber with said inert gasfilled chamber; an oil cushion in said spring chamber wherein a portionof said oil is displaced from said spring chamber through said fluidconduit and into said gas filled chamber as said piston is moved in thefirst longitudinal direction; and a floating annular piston slidablylocated in said inert gas filled chamber exposed on one side to saidpressurized inert gas and on a second side to said displaced oil. 17.The apparatus of claim 16 wherein said fluid conduit contains hydraulicimpedance means for impeding the rate of oil displacement from saidspring chamber to said inert gas filled chamber to thereby dampenmovements of said piston in the first longitudinal direction.
 18. An oilwell testing sampler for controlling the flow of well fluids through theconduit of a test string in a well bore, and for trapping a sample ofwell fluids therein; said sampler comprising: a cylindrical outerhousing assembly; upper and lower inner cylindrical housing members,both having a plurality of ports through the walls thereof, said membersbeing longitudinally spaced apart and located concentrically within andconnected to said outer housing assembly so as to provide an annularspace between each inner housing member and said outer housing assembly;a cylindrical sampler mandrel having an upper set of a plurality ofports and a lower set of a plurality of ports through the wall thereof,said sampler mandrel slidably located concentrically within said innerhousing members and spanning the space between said inner housingmembers to form an annular sample chamber between said outer housingassembly, said sampler mandrel, and said upper and lower inner housingmembers; and a pull mandrel having a plurality of longitudinal flowchannels along a portion of the sides of said pull mandrel, said pullmandrel extending from one end of said outer housing assembly betweensaid outer housing and one of said inner housing members and beinglinked to one end of said sampler mandrel through lOngitudinal slots insaid one of said inner housing members; said pull mandrel, whenconnected to an actuating tool in said test string, moving said samplermandrel from a closed position wherein said upper set and lower set ofports of said sampler mandrel do not communicate with the ports in saidupper and lower inner housing members; to an open position wherein saidupper set and lower set of ports of said sampler mandrel communicaterespectively with the ports in said upper and lower inner housingmembers with one set of communicating ports additionally communicatingwith said flow channels in said pull mandrel and with the other set ofcommunicating ports additionally communicating with the annular spacebetween the second of said inner housing members and said outer housingassembly, and to a second closed position wherein said upper set andlower set of ports of said sampler mandrel do not communicate with saidports in said upper and lower inner housing members.
 19. The sampler ofclaim 18 further comprising safety means for locking said samplermandrel in said second closed position after a predetermined force fromsaid actuating tool.
 20. The sampler of claim 19 wherein said safetymeans comprises a sleeve frangibly attached to said pull mandrel forabutting the tool string to which said sampler is attached, hinged proparms retained in the annular space between one of said inner housingmembers and said outer housing assembly while said sampler is in saidinitial closed or said open position, and means for biasing said proparms in locking engagement with said sampler mandrel when said samplermandrel moves to said second closed position.
 21. The sampler of claim20 wherein one of said inner housing members has a drain port adaptedfor attachment of a drain conduit therein, said sampler furthercomprising: a removable plug, threadably engaged in said inner housingmember for blocking fluid communication through the central bore of saidcylindrical inner housing member; said removable plug adapted to blocksaid drain port in one position, and to allow fluid communicationthrough said drain port in a second position.
 22. The sampler of claim21 further comprising a spool valve through the wall of said outerhousing assembly and communicating with the annular space between saidsecond inner housing member and said outer housing assembly; said spoolvalve having a first position for allowing fluid flow from the conduitof said test string into said sampler, and a second position forallowing the draining of fluids trapped within said outer housingassembly through the walls of said outer housing assembly.